KR20130019399A - Doped positive electrode active materials and lithium ion secondary battery constructed therefrom - Google Patents

Abstract

A cathode active material including a dopant in an amount of 0.1 to 10 mol% of magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), cadmium (Cd), or a combination thereof is disclosed. , They have a high specific discharge capacity during cycling at room temperature and intermediate discharge rates. Some materials of interest have the formula Li _{1 + x} Ni _α Mn _β-δ Co _γ A _δ X _μ O _{2 - z} F _z , where x is in the range of about 0.01 to about 0.3, and δ is about 0.001 to about 0.15 And the sum of x + α + β + γ + δ + μ may be approximately 1.0. The material may be coated with metal fluoride, in particular to improve the performance of the material during cycling. The material may generally have a tap density of at least 1.8 g / mL. In addition, the material may have an average discharge voltage of approximately 3.6V.

Description

A doped cathode active material and a lithium ion secondary battery manufactured therefrom {DOPED POSITIVE ELECTRODE ACTIVE MATERIALS AND LITHIUM ION SECONDARY BATTERY CONSTRUCTED THEREFROM}

The present invention relates to a doped cathode composition and a method of making the composition. In general, the doped cathode materials and compositions have a high specific capacity. The present invention also relates to a lithium secondary battery prepared from a doped cathode active material that provides high specific discharge capacity and long cycle life.

Lithium batteries are widely used in home appliances because of their relatively high energy density. Rechargeable batteries are also called secondary cells, and lithium ion secondary cells generally include a negative electrode material that introduces lithium when the battery is charged. In some commercial batteries, the negative electrode material may be graphite and the positive electrode material may include lithium cobalt oxide (LiCoO ₂ ). In fact, only a fraction of the theoretical capacity of the cathode can generally be used. At least two other lithium based cathode materials are also currently used commercially. These two materials are LiMn ₂ O ₄ with spinel structure and LiFePO ₄ with olivine structure. These other materials did not provide any significant improvement in energy density.

Lithium ion batteries can generally be classified into two categories depending on their application. The first category includes high power batteries, where lithium ion battery cells are designed to deliver high current (amps) in applications such as power tools and hybrid electric vehicles (HEVs). However, such battery cells are intentionally low in energy because designs for providing high current generally reduce the total energy that can be delivered from the battery. The second category of designs includes high-energy batteries, where lithium-ion battery cells are used to deliver higher full capacity cell phones, laptop computers, electric vehicles (EVs), and plug-in hybrid electric vehicles. Is designed to deliver low to medium currents (amps) in applications such as PHEVs.

Summary of the Invention

In one aspect, the present invention relates to a positive electrode active material comprising a composition having the formula Li _{1 + x} Ni _α Mn _β-δ Co _γ A _δ X _μ O _{2 - z} F _z , wherein x is from about 0.01 to about 0.3 Α is in the range of about 0.1 to about 0.4, β is in the range of about 0.25 to about 0.65, γ is in the range of about 0 to about 0.4, δ is in the range of about 0.001 to about 0.15, and μ is In the range from 0 to approximately 0.1, and z in the range from 0 to approximately 0.2. A is magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), cadmium (Cd), or a combination thereof, and X is A, nickel (Ni), manganese (Mn) And a transition metal different from cobalt (Co).

In another aspect, the invention provides a tenth cycle of at least approximately 240 mAh / g at room temperature with an average discharge voltage of at least approximately 3.63 volts at a discharge rate of C / 10, and a discharge rate of C / 3 when discharged from 4.6 volts to 2.0 volts. At least approximately 90% of the discharge capacity of the tenth cycle when cycled between the tenth and forty cycles at room temperature with a discharge capacity of the cycle, and a discharge rate of C / 3 from 4.6 volts to 2.0 volts. A positive electrode active material for a lithium ion battery having a discharge capacity of 40 cycles.

In another aspect, the present invention relates to a method for the synthesis of layered lithium metal oxide, the method comprising the step of precipitating a mixed metal hydroxide or carbonate component from a solution comprising a +2 metal cation, The mixed metal hydroxide or carbonate component has a selected stoichiometry comprising Ni ⁺² , Mn ⁺² , Co ⁺² having a dopant concentration of about 0.1 to about 10 mol%, wherein the dopant is magnesium (Mg), calcium ( Ca), strontium (Sr), barium (Ba), zinc (Zn), cadmium (Cd), or combinations thereof.

In a further aspect, the present invention provides a tenth cycle of at least approximately 240 mAh / g at room temperature with an average discharge voltage of at least approximately 3.63 volts at a discharge rate of C / 10 and a discharge rate of C / 3 when discharged from 4.6 volts to 2.0 volts. It relates to a positive electrode active material for a lithium ion battery having a discharge capacity of a cycle, and a discharge capacity of at least about 170 mAh / g at a 46th cycle at room temperature at a discharge rate of 2C from 4.6 volts to 2.0 volts.

1 is a schematic diagram of a battery structure separated from a container.
FIG. 2 is a graph showing X-ray diffraction patterns of 0, 0.5, 1, 2, 3, and 5% magnesium doped cathode active materials disclosed in Example 1. FIG.
FIG. 3 is a graph showing the specific discharge capacity versus cycle number of a battery formed from a Mg dopant free anode electroactive material with AlF ₃ coating compositions at 0, 3, 6, 22, and 40 nm.
4 is a graph showing the specific discharge capacity versus the number of cycles of a battery formed of a positive electrode electroactive material comprising 0.5 mol% magnesium with AlF ₃ coating compositions at 0, 3, 5, 6, 11, and 22 nm. Samples without Mg doping and AlF ₃ coating were included as controls.
5 is a graph showing the specific discharge capacity versus the number of cycles of a battery formed of a positive electrode electroactive material comprising 1.0 mol% magnesium with AlF ₃ coating compositions at 0, 3, 5, 6, 11, and 22 nm. Samples without Mg doping and AlF ₃ coating were included as controls.
FIG. 6 is a graph showing the specific discharge capacity versus number of cycles of a battery formed of a positive electrode electroactive material comprising 2.0 mol% magnesium with AlF ₃ coating compositions at 0, 3, 5, 6, 11, and 22 nm. Samples without Mg doping and AlF ₃ coating were included as controls.
FIG. 7 is a graph showing the specific discharge capacity versus cycle number of a battery formed of a positive electrode electroactive material comprising 3.0 mol% magnesium with AlF ₃ coating compositions at 0, 3, 5, 6, 11, and 22 nm. Samples without Mg doping and AlF ₃ coating were included as controls.
FIG. 8 is a graph showing the specific discharge capacity versus cycle number of a battery formed of a positive electrode electroactive material comprising 5.0 mol% magnesium with AlF ₃ coating compositions at 0, 3, 5, 6, 11, and 22 nm. Samples without Mg doping and AlF ₃ coating were included as controls.
FIG. 9 is a graph showing the specific discharge capacity versus the number of cycles of a battery without AlF ₃ coating composition and formed of a positive electrode active material comprising 0, 0.5, 1, 2, 3, 5 mol% magnesium.
FIG. 10 is a graph showing first cycle specific discharge capacity versus mole percentage at a discharge rate of C / 10 of magnesium with AlF ₃ coating compositions at 0, 3, 6, 11, and 22 nm.
FIG. 11 is a graph showing the ninth cycle specific discharge capacity versus mole percentage at a discharge rate of C / 3 of magnesium with AlF ₃ coating compositions at 0, 3, 6, 11, and 22 nm.
12 is a graph showing the 41st cycle specific discharge capacity versus mole percentage at 1C discharge rate of magnesium with AlF ₃ coating compositions at 0, 3, 6, 11, and 22 nm.
FIG. 13 is a graph showing 46th cycle specific discharge capacity vs. mole percentage at 2C discharge rate of magnesium with AlF ₃ coating compositions at 0, 3, 6, 11, and 22 nm.
FIG. 14A is a graph showing the average discharge cycle average voltage versus thickness of an AlF ₃ coating with Mg doping of 0, 0.5, 1, 2, 3, and 5 mol%.
14B is a graph showing the average voltage of one discharge cycle versus mole percentage of magnesium in the uncoated composition.
15 is a graph showing the average voltage versus mole percentage of one discharge cycle of magnesium with AlF ₃ coating compositions at 0, 3, 6, 11, and 22 nm.
FIG. 16A is a graph showing irreversible capacity loss versus thickness of the first cycle of AlF ₃ coating with Mg doping of 0, 0.5, 1, 2, 3, and 5 mol%.
FIG. 16B is a graph showing the irreversible capacity loss versus mole percentage of the first cycle of magnesium of the uncoated composition.
FIG. 17 is a graph showing the irreversible capacity loss versus mole percentage of the first cycle of magnesium with AlF ₃ coating compositions at 0, 3, 6, 11, and 22 nm.
FIG. 18 shows a complex impedance for a battery having a 100% state of charge formed from an uncoated cathode active material having a non-magnesium dopant, 1 mol% Mg dopant, 3 mol% Mg dopant, and 5 mol% Mg dopant. Is a graph of.
19 is an enlarged view of a portion of the graph of the complex impedance of FIG. 18.
FIG. 20 shows lithium diffusion constants obtained from complex impedance measurements for a battery formed of an uncoated cathode active material having a non-magnesium dopant, 1 mol% Mg dopant, 3 mol% Mg dopant, and 5 mol% Mg dopant. ) Is a graph.
FIG. 21 is a graph of complex impedance for a battery having a 100% state of charge formed of an uncoated cathode active material having a non-magnesium dopant, 1 mol% Mg dopant, 3 mol% Mg dopant, or 5 mol% Mg dopant.

Doped lithium-rich lithium metal oxides have been proposed as more stable positive electrode active compositions during high voltage cycles of lithium ion batteries. In particular, doping can provide desirable performance for lithium-rich compositions represented by the formula Li _{1 + x} M _{1 -xy} A _y 0 _2-z F _z , where M generally comprises manganese (Mn) A is a combination of metals and A is a dopant metal generally having an oxidation state of +2. Fluorine is an optional anion dopant. High specific amount doped cathode materials for lithium ion secondary batteries can be produced using processes that provide improved energy performance and can be extended for commercial production. Suitable synthesis processes include, for example, a co-precipitation approach. In some embodiments, the dopant element (A) is included as part of the metal salt on the solution prior to the step of precipitating the metal carbonate or hydroxide for further processing. Particularly the stoichiometry of the dopant in the active material of interest provides the desirable properties for the positive electrode material in commercial applications. The material has good cycle characteristics and overall capacity as a result of the relatively high tap density combined with high specific capacity. The material may also have a high average voltage, low impedance, and low irreversible capacity loss of the first cycle. The use of metal fluoride coatings or other suitable coatings also provides cycle improvement.

The positive electrode material disclosed herein can be used to construct batteries having a combination of good cycle performance, high specific capacity, high overall capacity, high average voltage, improved speed, and low impedance. The manufactured lithium ion batteries can be used as an improved power source, particularly for high energy applications such as electric vehicles, plug-in hybrid vehicles and the like. The positive electrode material exhibits a high average voltage during the discharge cycle and therefore the battery has a high output with high specific capacity. As a result of the high tap density and good cycle performance, the battery exhibits a sustained high overall capacity when cycled. The positive electrode material also exhibits a reduced rate of irreversible capacity loss after the first charge and discharge of the battery, so that the negative electrode material can be reduced if desired.

The battery disclosed herein is a lithium ion battery, wherein the non-aqueous electrolyte solution comprises lithium ions. In secondary lithium ion batteries, lithium ions are released from the negative electrode upon discharge, and thus the negative electrode acts as an anode. In addition, during discharge, oxidation of lithium at the cathode causes the production of electrons. Accordingly, the anode serves as a cathode that absorbs lithium ions through insertion or a similar process during discharge to consume electrons during discharge. Upon recharging the secondary battery, the flow of lithium ions is reversed through a battery having a negative electrode that absorbs lithium and a positive electrode that releases lithium as lithium ions.

The word "element" is used herein in a conventional manner, as indicated by the construction of the periodic table, where the element has an appropriate oxidation state when present in the composition, and only in elemental form M ⁰ when specified in elemental form. exist. Thus, metal elements generally exist only in the metallic state in elemental form or in the corresponding alloy in the elemental form of metal. In other words, metal oxides or other metal compositions other than metal alloys are generally not metallic.

The lithium ion battery may use a lithium-rich positive electrode active material as compared to the standard uniform electroactive lithium metal oxide. While not wishing to be bound by theory, in some embodiments, suitably formed lithium-rich lithium metal oxides are believed to have a complex crystal structure. While certain compositions of interest have some of the manganese cations substituted with other transition metal cations with appropriate oxidation states, for example, in some embodiments of lithium-rich materials, the Li ₂ MnO ₃ material is a layered LiM ′. Structurally integrated with O ₂ components or similar composite compositions. In some embodiments, the positive electrode material may be represented by two component notation xLi ₂ MO _3. (1-X) LiM'O ₂ , where M 'is at least one of Mn ⁺³ or Ni ⁺³ . One or more metal cations having an average valence of +3 with a cation of M, and one or more metal cations having an average valence of +4. These compositions are further disclosed, for example, in US Pat. No. 6,680,143 ('143 patent) to Thackeray et al. Entitled “Lithium Metal Oxides for Lithium Cells and Batteries”, incorporated herein by reference.

In particular, the positive electrode active material of interest is typically the formula Li _{1 + x} Ni _α Mn _β-δ Co _γ A _δ X _μ O _{2 -} can be represented by _z F _z, where x is in the range of about 0.01 to about 0.3, α is approximately Is in the range of 0.1 to about 0.4, β is in the range of about 0.25 to about 0.65, γ is in the range of about 0 to about 0.4, δ is in the range of about 0.001 to about 0.15, and μ is in the range of 0 to about 0.1 , z ranges from 0 to approximately 0.2, where A is magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), cadmium (Cd), or a combination thereof Is a transition metal separate from A, nickel (Ni), manganese (Mn) and cobalt (Co) or a combination thereof. X and F are optional dopants. Similar but more general compositions are described in U.S. Patent Application No. 12 of Venkatachalam et al. Entitled "Anode Materials for Lithium Ion Batteries with High Specific Discharge Capacities and Processes for Synthesis of These Materials," incorporated herein by reference. US Patent Application No. 12 / 332,735 ('735 Application) to Lopez et al. Entitled " 246,814 "(' 814 application) and " positive material for high specific discharge capacity lithium ion batteries ". The surprisingly good performance for the Li [Li _{0 .2 0 .175} Ni Co Mn _{0 .10 .525 0]} O _2, by using a co-precipitation synthesis methods as disclosed in 735 Application, 814 Application and 'was achieved. As disclosed herein, desirable properties have been achieved in which a non-extractable redox active material is replaced by an unextractable stable +2 valent metal ion that is a dopant. The dopant element does not substantially change the crystal structure compared to the reference composition in which the amount of manganese is increased to stoichiometrically replace the amount of dopant to keep the metal content the same.

The formulas presented herein are based on the molar quantity of starting material in the synthesis and can therefore be determined accurately. For many metal cations, it is generally believed that they are incorporated quantitatively into the final material with unknown important pathways leading to the loss of metal from the resulting composition. Of course, many metals have a number of oxidation states associated with their activity for batteries. Due to the large number of oxidation states and the presence of a large number of metals, the exact stoichiometry for oxygen is generally estimated roughly, as is conventional in the art. However, based on the crystal structure, the overall stoichiometry for oxygen is properly estimated. All protocols and related issues discussed herein in this paragraph are routine in the art and are a long established way of relating these issues in the art.

Substitution of a portion of manganese or cobalt with a dopant metal leads to metals with desirable properties. Published US Patent Application No. 2007 / 0111098A ('Sun, et al., Entitled "Anode Active Material for Lithium Secondary Battery, Process for Making the Same, and Reactor for Use in the Process," incorporated herein by reference) 098). The doped material in the '098 application is referred to as lithium cobalt oxide. The compositions exemplified in the '098 application have no lithium concentration as compared to LiMO2 and have a lower capacity than the compositions disclosed herein.

For the +2 metal dopant, manganese may be particularly preferred due to its particular oxidation potential and moderate price. In some embodiments, the sum of x + α + β + γ + δ + μ of the positive electrode active material, Li _{1 + x} Ni _α Mn _β-δ Co _γ A _δ X _μ O _{2 − z} F _z , is approximately 1.0. A can be considered a dopant in the crystalline material, and the material has a molar percentage of A of about 1.0 to about 10%. With this stoichiometry, the material can form a layer-layer composite crystal structure corresponding to the two materials represented by b Li ₂ MO ₃ · (1-6) LiM'O ₂ . Wherein M 'is one or more metal cations having an average valence of +3 with at least one cation being Mn or Ni, and M is one or more metal cations having an average valence of +4. General compositions are further disclosed, for example, in US Pat. No. 6,680,143 ('143 patent) to Thackeray et al. Entitled “Lithium Metal Oxides for Lithium Cells and Batteries”, incorporated herein by reference. Fluorine is an optional anionic dopant that substitutes for oxygen.

In materials of particular interest, lithium is an extractable metal when the material is incorporated into the anode. In particular, when the battery is charged, as lithium is absorbed by the active material of the negative electrode, a substantial portion of lithium can be extracted from the material. In materials of particular interest, the dopant element has a stable oxidation state of +2, and the element is of the composition of group IIA (column 2) or group IIB (column 12) of the periodic table. The use of these dopants in the high voltage, lithium-rich compositions disclosed herein has been found to provide stability to materials that cause high capacity, improved high voltage cycles, improved speed capability, and low impedance, while maintaining relatively stable average voltages. lost.

These compositions disclosed herein have a low risk of fire due to the specific components having a layered structure and, in some embodiments, with improved safety properties due to the reduced amount of nickel compared to some other high capacity cathode materials. In some embodiments, the compositions can be prepared from starting materials that use lesser amounts of elements that are less desirable from an environmental point of view, and have reasonable costs for commercial scale production.

Carbonate and hydroxide coprecipitation methods have been performed for the preferred lithium-rich metal oxides disclosed herein, which exhibit high specific capacity performance with dopants of +2 valence, such as magnesium. As disclosed herein, improved compositions can be obtained using coprecipitation as an intermediate component of hydroxides or carbonates, and solutions are generally formed in which metal hydroxides or carbonates precipitate to the desired metal stoichiometry. The metal hydroxide or carbonate component from the coprecipitation may then be heat treated to form the corresponding metal oxide with appropriate crystallinity. Lithium cations may be incorporated in the initial coprecipitation process, or lithium may be introduced during or after heat treatment into the solid state reaction to form oxides from the hydroxide or carbonate component. As demonstrated in the examples below, the lithium-rich metal oxides formed by the coprecipitation process have improved performance characteristics.

When a corresponding battery with an insertion-based positive electrode active material is used, insertion and desorption of lithium ions from the lattice induces a change in the crystal lattice of the electroactive material. As long as these changes are inherently reversible, the capacity of the material does not change significantly. In general, the capacity of the active material used in the lithium ion secondary battery is observed to decrease with various cycles. Thus, after a number of cycles, the battery's performance falls below an acceptable value and the battery is replaced. In addition, on the first cycle of the battery, there is generally an irreversible capacity loss that is significantly greater than the capacity loss per cycle in subsequent cycles. The irreversible capacity loss is the difference between the charge capacity of the new battery and the first discharge capacity. To compensate for this irreversible capacity loss of the first cycle, additional electroactive material is included in the cathode, so that the battery is fully charged even if this loss capacity is not available for most of the life of the battery so that the cathode material is essentially wasted To be possible. Most of the irreversible capacity loss of the first cycle is usually due to the anode material.

The doped cathode active materials disclosed herein exhibit improved capacity, cycle characteristics, speed function, and irreversible capacity loss of the first cycle. In addition, suitable coating materials can be used to improve both battery capacity and long-term cycle performance of the material, as well as further reduce irreversible capacity loss of the first cycle. Without wishing to be bound by theory, the coating stabilizes the crystal lattice upon absorption and desorption of lithium ions, thereby significantly reducing irreversible changes in the crystal lattice. In particular, the metal fluoride component can be used as an effective coating. The general use of metal fluoride components, in particular LiCoO ₂ and LiMn ₂ O ₄ , as coatings for cathode active materials is a line entitled “Cathode Active Materials Coated with Fluorine Compounds for Lithium Secondary Batteries and Methods for Making the Same”, incorporated herein by reference. And published PCT application WO 2006 / 109930A. An improved fluoride coating is disclosed in US Patent Application No. 12 / 616,226 to Venkatachalam entitled "Coated Anode Material for Lithium Ion Batteries", incorporated herein by reference.

It has been found that metal fluoride coatings can provide significant improvements to the lithium-rich layered cathode active materials disclosed herein. This improvement is associated with long-term cycles due to a significantly reduced capacity drop, a significant reduction in the irreversible capacity loss of the first cycle, and a general capacity improvement. The thickness of the coating material can be chosen to highlight the observed performance improvements.

As disclosed herein, lithium-rich positive electrode active materials having a composite crystal structure and a suitable coating may exhibit a large specific density as well as a large tap density. In general, when the specific quantities are comparable, the higher tap density of the positive electrode material provides a higher overall capacity of the battery. The positive electrode material disclosed herein with high tap density in addition to high specific capacity can thus be used to construct batteries with significantly improved performance. In the charge / discharge measurement, it is important to note that the specific amount of a material is determined by the discharge rate. The maximum specific capacity of a particular material is measured at very low discharge rates. In practical use, the actual specific capacity is below the maximum due to a limited rate of discharge. More realistic specific capacities can be measured using reasonable discharge rates that are more similar to speed in use. For low to medium rate applications, reasonable test rates include battery discharge over three hours. In conventional notation it is denoted C / 3 or 0.33C. The positive electrode active material disclosed herein may have a specific discharge capacity of at least approximately 240 mAh / g with a discharge rate of c / 3 at room temperature when discharged at 4.6 volts with a tap density of 1.8 g / mL or greater.

Rechargeable batteries have a variety of uses, such as transportation devices such as automobiles and forklifts, as well as mobile communication devices such as widely used telephones, portable entertainment devices such as MP3 players, televisions, portable computers, and combinations of these devices. Most batteries used in these electronic devices have a fixed volume. It is therefore highly desirable for the positive electrode material used in such batteries to have a high tap density, so there is an inherently more chargeable material in the positive electrode that yields the higher total capacity of the battery. Batteries disclosed herein, which incorporate improved cathode active materials for specific volume, tap density, and cycle, can provide improved performance in consumer electronics, particularly medium current applications.

Battery structure

Referring to FIG. 1, a battery 100 having a cathode 102, an anode 104, and a separator 106 between the cathode 102 and the anode 104 is schematically illustrated. The battery may include a plurality of positive electrodes and a plurality of negative electrodes with properly disposed separators, such as in a stack. The electrolyte in contact with the electrodes provides ionic conductivity through the separator between the electrodes of opposite polarity. Batteries generally include current collectors 108 and 110 associated with negative electrode 102 and positive electrode 104, respectively.

Lithium has been used in both primary and secondary batteries. An attractive feature of lithium metal is the fact that it is light and that it is the most electropositive metal, and aspects of these features can advantageously also be captured in lithium ion batteries. Certain types of metals, metal oxides and carbon materials are known to introduce lithium ions into a structure through insertion, alloying or similar mechanisms. Preferred mixed metal oxides are also disclosed herein and serve as an electroactive material for the positive electrode in secondary lithium ion batteries. The lithium ion battery refers to a battery that is a substance in which a negative electrode active material absorbs lithium during charging and desorbs lithium during discharge. If lithium metal itself is used as the anode, the battery produced is generally referred to simply as lithium battery.

The nature of the negative electrode insertion material affects the voltage of the battery since the voltage is the difference between the half cell potential at the cathode and the anode. Suitable lithium intercalating compositions for negative electrodes are, for example, graphite, synthetic graphite, coke, fullerene, niobium pentoxide, tin alloys, silicon, titanium oxide, tin oxide And lithium titanium oxides such as Li _x TiO ₂ (0.5 <x ≦ ₁ ) or Li _{1 + x} Ti _{2 − x} O ₄ (0 ≦ _x ≦ 1/3). Further negative electrode materials are disclosed in Kumar published U.S. Patent Application No. 2010/0119942 and "Specific negative electrode compositions" entitled "Compound Compositions, Negative Electrodes with Composite Compositions and Batteries", incorporated herein by reference. Published in US Patent Application No. 2009/0305131 to Kumar et al. Entitled "Lithium Ion Batteries."

The positive electrode active composition and the negative electrode active composition are generally powder compositions that are received together at the corresponding electrode by a polymeric binder. The binder provides ionic conductivity to the active particles when in contact with the electrolyte. Suitable polymeric binders are, for example, polyvinylidene fluoride, polyethylene oxide, polyethylene, polypropylene, polytetrafluoroethylene, polyacrylates, for example ethylene-propylene Rubbers such as ethylene-propylene-diene monomer (EPDM) rubber or styrene butadiene rubber (SBR), copolymers thereof or mixtures thereof. The particles loaded into the binder can be very large, such as at least about 80 wt%. To form the electrode, the powder can be mixed with the polymer in a suitable liquid, such as a solvent for the polymer. The resulting paste may be pressed into the electrode structure. In some embodiments, it may be desirable to use a polymeric binder with a high molecular weight. In some embodiments, the battery may be constructed based on the method disclosed in published US patent application 2009/0263707 to Buckley et al. Entitled “High Energy Lithium Ion Secondary Cell”, incorporated herein by reference. .

The positive electrode composition, and possibly the negative electrode composition, also generally includes an electrically conductive powder that is different from the electroactive composition. Suitable further electrically conductive powders include, for example, metal powders such as graphite, carbon black, silver powders, metal fibers such as stainless steel fibers and the like and combinations thereof. In general, the anode may comprise about 1 wt% to 25 wt%, and in yet another embodiment about 2 wt% to 15 wt% of other electrically conductive powder. One of ordinary skill in the art will recognize that additional ranges for the amount of electrically conductive powder within the above stated ranges may be considered and are included in the present disclosure.

In general, each electrode is associated with an electrically conductive current collector to facilitate the flow of electrons between the electrode and the external circuit. The current collector may comprise a metal, such as a metal foil or a metal grid. In some embodiments, the current collector may be formed of nickel, aluminum, stainless steel, copper, or the like. The electrode material may be formed into a thin film on the current collector. The electrode material having the current collector can be dried, for example, in an oven to remove the solvent from the electrode. In some embodiments, the dried electrode material in contact with the current collector foil or other structure may be subjected to a pressure, such as approximately 2 to 10 kg / cm ² (kg per square centimeter).

The separator is located between the positive and negative electrodes. The separator is electrically insulated while providing at least selected ion conduction between the two electrodes. Various materials can be used as the separator. Commercial separator materials are generally formed of polymers such as polyethylene and / or polypropylene, which are porous sheets that provide ionic conduction. Commercial polymeric separators include, for example, Celgard® separator materials from Hoechst Celanese, Charlotte, N. C .. Ceramic-polymer composites have also been developed for separator applications. Such composite separators can be stable at high temperatures and the composite material can significantly reduce the risk of fire. Polymer-ceramic composites for separator materials are further described in published US patent application 2005 / 0031942A to Hennige et al. Entitled “Electrical Separator, Methods for Making and Use thereof”, incorporated herein by reference. Is disclosed. Polymer-ceramic composites for lithium ion battery separators are sold under the trademark Separion® of Evonik Industries, Germany.

We refer to a solution comprising solvated ions as electrolyte, and the ionic composition that decomposes to form solvated ions in a suitable liquid is called an electrolyte salt. The electrolyte for a lithium ion battery may comprise one or more selected lithium salts. Suitable lithium salts generally have inert anions. Suitable lithium salts are, for example, lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium bis (trifluoromethyl sulfonyl imide) Lithium trifluoromethane sulfonate, Lithium tris trifluoromethyl sulfonyl methide, Lithium tetrafluoroborate, Lithium perchlorate ), Lithium tetrachloroaluminate, lithium chloride, lithium difluoro oxalato borate, and combinations thereof. Traditionally, electrolytes contain lithium salts at a concentration of 1 M.

For lithium ion batteries of interest, generally non-aqueous liquids are used to dissolve the lithium salt (s). The solvent generally does not dissolve the electroactive material. Suitable solvents are, for example, propylene carbonate, dimethyl carbonate, diethyl carbonate, 2-methyl tetrahydrofuran, dioxolane, tetra Hydrofuran, methyl ethyl carbonate, γ-butyrolactone, dimethyl sulfoxide, acetonitrile, formamide, dimethyl formamide, triglyme (tri (ethylene glycol) dimethyl Ether) (triglyme (tri (ethylene glycol) dimethyl ether)), diglyme (diethylene glycol dimethyl ether), glyme or 1.2-dimethoxyethane or ethylene glycol dimethyl ether (glyme or 1,2-dimethyloxyethane or ethylene glycol dimethyl ether (DME), nitromethane and mixtures thereof. Particularly useful solvents for high voltage lithium-ion batteries are US patents of Amiruddin et al., Filed Dec. 4, 2009, entitled “Lithium Ion Batteries with High Voltage Electrolyte and Additives,” which is incorporated herein by reference. It is further disclosed in Application 12 / 630,992.

The electrodes disclosed herein can be incorporated into a variety of commercial battery designs. For example, the cathode composition can be used for prismatic shaped batteries, wound cylindrical batteries, coin shaped batteries or other suitable battery shapes. The tests in the examples below are performed using coin type batteries. The battery may comprise a single cathode structure or multiple cathode structures assembled into parallel and / or series wiring (s). While positive electrode active materials can be used for primary or single charging applications in batteries, the batteries formed generally have desirable cycle characteristics for secondary cell applications over several cycles of the battery.

In some embodiments, the positive electrode and the negative electrode can be laminated with a separator therebetween, and the formed laminate structure can be rolled into a cylindrical or angular configuration to form a battery structure. Suitable electrically conductive tabs are welded to the current collector, and thus the jellyroll structure can be placed in a metal canister or polymer package with negative and positive electrode tabs welded to suitable external contacts. have. The electrolyte is added to the canister, and the canister is sealed to complete the battery. Some rechargeable commercial batteries currently in use include, for example, cylindrical 18,650 batteries (18 mm diameter and 65 mm length) and 26,700 batteries (26 mm diameter and 70 mm length), but other battery sizes May also be used.

Cathode active material

The positive electrode active material includes a lithium intercalating metal oxide. In some embodiments, the lithium metal oxide may comprise a lithium-rich composition, generally believed to form a layered composite crystal structure. It has been found that doping of metal ions of +2 valence can also stabilize and improve the performance of the formed composition. In some embodiments, the composition further comprises nickel (Ni), cobalt (Co) and manganese (Mn) ions. It has been surprisingly found that dopants improve the performance of the composition formed for doses after cycles. In addition, for the coated sample, the average voltage can be increased with doping and a slight decrease in irreversible capacity loss was also found. Desired electrode active materials can be synthesized using the synthesis methods disclosed herein.

In a particularly interested part composition, the composition formula Li _{1 + x} Ni _α Mn _β-δ Co _γ A _δ X _μ O _{2 -} is represented by _z F _z, where x is in the range of approximately 0.01 to approximately 0.3, α is in the range of about 0.1 to about 0.4, β is in the range of about 0.25 to about 0.65, γ is in the range of about 0 to about 0.4, δ is in the range of about 0.001 to about 0.15, and μ is 0 to about 0.1 And z is in the range of 0 to approximately 0.2, wherein A is magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), cadmium (Cd), or a combination thereof , X is an optional transition metal dopant other than A, nickel (Ni), manganese (Mn) and cobalt (Co) or a combination thereof. In some embodiments, the sum of x + α + β + γ + δ + μ of the positive electrode active material is approximately 1.0. With respect to the amount of dopant A present in the composition, δ in further embodiments is from about 0.0025 to about 0.12, and in other embodiments from about 0.005 to about 0.11, and in further embodiments from about 0.01 to about 0.10. The amount of dopant A may be selected such that the crystal structure of the material is substantially unchanged relative to the crystal structure of the reference composition having a stoichiometry of Li _{1 + x} Ni _α Mn _β Co _γ O _{2 - z} F _z . Those skilled in the art will appreciate that additional ranges of parameter values can be considered and are included in the present disclosure within the explicit ranges noted above. In general, it is desirable to provide an inert inorganic coating to further stabilize the material. Coating is further disclosed in other sections below.

In connection with some embodiments of the materials disclosed herein, Thackery and colleagues have proposed a composite crystal structure for some lithium-rich metal oxides, wherein the Li ₂ MO ₃ composition is structurally Li ₂ M'O. _It is integrated into a layered structure with _two components. The electrode material may be represented by the bicomponent notation b Li ₂ MO ₃ · (1-b) LiM'O ₂ , where M 'has an average valence of +3 and is at least one of manganese (Mn) or nickel (Ni) One or more metal elements with elements of M, M is a metal element having an average valence of +4, 0 <b <1, and in some embodiments 0.03 ≦ b ≦ 0.9. For example, M 'can be a combination of Ni ⁺² , Co ⁺² and Mn ⁺² . The general formula for these compositions can be represented as Li _{1 + b / (2 + b)} M _{2b / (2 + b)} M ' _{(2-2b) / (2 + b)} O ₂ . This formula is consistent with the sum of x + α + β + γ + δ + μ, which is 1 in the formula of the previous paragraph, where x = b / (2 + b). Batteries made with these materials were observed to cycle at higher voltages and higher capacities than batteries made with the corresponding LiMO ₂ compositions. Such materials are described in US Pat. No. 6,680,143 to Thackery et al. Entitled "Lithium Metal Oxide Electrodes for Lithium Cells and Batteries" and "Lithium Metal Oxide Electrodes for Lithium Cells and Batteries", incorporated herein by reference. US Pat. No. 6,677,082 to Thackery et al. Saccharie was of particular interest for M 'and identified manganese (Mn), titanium (Ti) and zirconium (Zr) and M for manganese (Mn) and nickel (Ni).

The structure of some specific layered structures is described in Thackery et al., "Li-rich Li _{1 + x} M _{1 - x} O ₂ electrodes for lithium batteries, where M is Mn, Ni, Co). In the comments on the structural complexity of "(Electrochemistry Communications 8 (2006), 1531-1538). The research reported in this paper has the formula _{Li 1 + x [Mn 0 .5} Ni 0 .5] 1- x O 2 and _{Li 1 + x [Mn 0 .333} Ni 0 .333 Co 0 .333] 1- x O _The composition which has ₂ was examined. The paper also discloses the structural complexity of layered materials.

Recently, Kang and colleagues have _disclosed compositions for use in secondary batteries having the formula Li _{1 + x} Ni _α Mn _β Co _γ M ′ _δ O _{2 − z} F _z , where M ′ is magnesium (Mg), zinc (Zn), aluminum (Al), gallium (Ga), boron (B), zirconium (Zr), titanium (Ti), x is between about 0 to 0.3, and α is about 0.2 to 0.6 Is between about 0.2 and 0.6, γ is between about 0 and 0.3, δ is between about 0 and about 0.15, and z is between about 0 and about 0.2. The metal range and fluorine have been proposed to improve battery capacity and stability of the layered structure formed during electrochemical cycles. See US Pat. No. 7,205,072 ('072 Patent) to Kang et al. Entitled "Layered Cathode Materials for Lithium Ion Secondary Batteries", incorporated herein by reference. This reference reported cathode materials having a capacity of less than 250 mAh / g (milli-amperes per gram) at room temperature after 10 cycles of unspecified speed, which is estimated to be low to increase performance. Note that fluorine substitutes for oxygen in this case. Kang et al. Reviewed a variety of specific compositions, including Li 1.2 Ni 0.15 Mn 0.55 Co 0.10 O 2, similar to the compositions discussed in the examples below, except for magnesium doping.

 The results obtained in the '072 patent include solid state synthesis of materials that did not achieve comparable cycle capacities for batteries made from cathode active materials formed by coprecipitation. The improved performance of the materials formed by the coprecipitation method is further described in the above-mentioned '814 and' 735 applications. Coprecipitation for the doped materials disclosed herein is further disclosed below.

Fluorine dopants have been proposed to improve performance, as disclosed in the '072 patent. It has been suggested that fluorine dopant introduction is reduced or eliminated at higher temperatures due to the volatility of LiF at high reaction temperatures. See Luo et al. “About the Introduction of Fluorine in Manganese Spinel Cathode Grids” (Solid State Ionics 180 (2009) 703-707). However, reasonable adjustment of the reaction conditions may appear to provide some fluorine doping through the high temperature process. The use of fluorine dopants in lithium-rich metal oxides to achieve improved performance is referred to herein as "High Fluorine Doped Lithium-Rich Metal Oxide Anode Battery Materials and Corresponding Batteries", incorporated herein by reference. Kumar et al., Published US patent application 2010/0086854. Thus, fluorine dopants may provide additional benefits to compositions doped with +2 metal ions. The fluorine dopant can be introduced, for example, using MgF ₂ during the oxide formation step or during the reaction of NH ₄ HF ₂ with an oxide already formed, for example at a temperature of approximately 450 ° C.

The performance of the positive electrode active material is affected by various factors. With respect to the doped material, the amount of dopant affects the properties formed, as disclosed herein. Average particle size and particle size distribution are two basic characteristics that characterize the positive electrode active material, and these properties affect the rate capability and tap density of the material. Since the battery has a fixed volume, it is preferable that the material used for the positive electrode of such a battery has a high tap density if the specific capacity of the material can be maintained at a preferably high value. And, the total capacity of the battery may be higher due to the presence of more chargeable materials at the positive electrode.

Synthesis method

The synthesis methods disclosed herein can be used to form doped forms of layered lithium-rich positive electrode active materials having improved specific capacity and high tap density during cycles.

Synthesis of the formula Li _{1 + x} Ni _α Mn _β-δ Co _γ A _δ X _μ O _{2 -} has been modified for the synthesis of a composition having a _z F _z, where x is in the range of about 0.01 to about 0.3, α is Is in the range of about 0.1 to about 0.4, β is in the range of about 0.25 to about 0.65, γ is in the range of about 0 to about 0.4, δ is in the range of about 0.001 to about 0.15, and μ is in the range of 0 to about 0.1. And z ranges from 0 to approximately 0.2, where A is magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), cadmium (Cd), or a combination thereof, X is a transition metal other than A, nickel (Ni), manganese (Mn) and cobalt (Co) or a combination thereof. In some embodiments, the sum of x + α + β + γ + δ + μ of the positive electrode active material is approximately 1.0, which is set through the choice of reactants of the synthesis. Synthetic methods are also suitable for commercial scale. Specifically, coprecipitation can be used to synthesize desired lithium-rich positive electrode materials with desirable results. In addition, solution-based precipitation methods, discussed in detail below, can be used to coat the material with metal fluoride.

In the coprecipitation method, the metal salt is dissolved in a preferred molar ratio in an aqueous solvent such as purified water. Suitable metal salts include, for example, metal acetate, metal sulfate, metal nitrate and combinations thereof. The concentration of the solution is generally chosen between 1 M and 3 M. The relative molar amount of the metal salt can be selected based on the desired formula of the product. Likewise, dopant elements may be introduced with other metal salts at appropriate molar amounts to cause the dopant to be introduced into the precipitated material. The pH of the solution is adjusted with the addition of Na ₂ CO ₃ and / or ammonium hydroxide to precipitate the metal hydroxide or carbonate with the desired amount of metal element. In general, the pH may be adjusted to a value between about 6.0 and about 12.0. The solution can be heated and stirred to promote precipitation of hydroxides or carbonates. Precipitated metal hydroxides or carbonates can be separated from the solution, washed and dried to form a powder prior to further processing. For example, drying may be carried out in an oven at approximately 110 ° C. for approximately 4 to 12 hours. Those skilled in the art will recognize that additional ranges of process parameters may be considered and are included in the present disclosure, within the explicit scope set forth above.

The collected metal hydroxide or carbonate powder may then be heat treated to convert the hydroxide or carbonate component to the corresponding oxide component through removal of water or carbon dioxide. Fluorine dopants can be introduced by adding fluorides such as MgF ₂ . In general, the heat treatment can be carried out in an oven, a furnace or the like. The heat treatment may be performed in an inert atmosphere or in the presence of oxygen. In some embodiments, the material may be heated to a temperature of at least about 350 ° C. and in some embodiments from about 400 ° C. to 800 ° C. to convert the hydroxide or carbonate to an oxide. In general, the heat treatment can be performed for at least about 15 minutes, in another embodiment from about 30 minutes to 24 hours or more, and in further embodiments from about 45 minutes to about 15 hours. Another heat treatment may be performed to improve the crystallinity of the product. This firing step for forming the crystalline product is generally performed at a temperature of at least about 650 ° C., in some embodiments from about 700 ° C. to about 1,200 ° C., and in still other embodiments from about 700 ° C. to about 1,100 ° C. The firing step to improve the structural properties of the powder can generally be carried out for at least 15 minutes, in another embodiment from about 20 minutes to about 30 hours or more, and in other embodiments from about 1 hour to about 36 hours. If desired, heating steps through an appropriate rise in temperature to obtain the desired material can be combined. Those skilled in the art will recognize that additional ranges of temperature and time may be considered and are included in the present disclosure within the above stated ranges.

Elemental lithium may be introduced into the material at one or more selected steps in the process. For example, lithium salt may be introduced into the solution prior to or during the precipitation step through the addition of a hydrated metal salt. In this method, lithium species are introduced into the hydroxide or carbonate in the same way as other metals. In addition, due to the nature of lithium, lithium element can be introduced into the material in a solid state reaction without adversely affecting the properties of the resulting composition. Thus, for example, an appropriate amount of lithium source as a powder, such as LiOH.H ₂ O, LiOH, Li ₂ CO _3, or a combination thereof, may be mixed with the precipitated metal carbonate or metal hydroxide. The powder mixture then forms an oxide through the heating step (s) and also forms a crystalline end product.

Further details of the hydroxide coprecipitation method are disclosed in the above-mentioned '814 application. Further details of the carbonate coprecipitation method are disclosed in the above-mentioned '735 application.

Coating and method for forming the coating

Inert inorganic coatings, such as metal fluoride coatings, have been found to significantly improve the performance of the lithium-rich layered cathode active materials disclosed herein. In particular, although the cycling characteristics of batteries made of metal fluoride coated lithium metal oxides have been found to significantly improve the cycling characteristics of batteries made of uncoated materials, inert metal oxide coatings have also been found to provide desirable properties. lost. In addition, the overall capacity of the battery also exhibits desirable properties due to the fluoride coating and the irreversible capacity loss of the first cycle of the battery is reduced. As discussed earlier, the irreversible capacity loss of the first cycle of a battery is the difference between the charging capacity of the new battery and its first discharge capacity. Much of the irreversible capacity loss of the first cycle is generally due to the anode material. If the coating is appropriately selected, this advantageous property from the coating is retained for the doped composition.

The coating provides an unexpected improvement in the performance of the high capacity lithium-rich compositions disclosed herein. In general, selected metal fluorides or metalloid fluorides may be used for the coating. Similarly coatings of metal and / or metalloid elements can be used. Metal / metalloid fluoride coatings have been proposed to stabilize the performance of positive electrode active materials for lithium secondary batteries. Suitable metal and metalloid elements for fluoride coatings are, for example, aluminum (Al), bismuth (Bi), gallium (Ga), germanium (Ge), indium (In), magnesium (Mg), lead (Pb) , Silicon (Si), tin (Sn), titanium (Ti), thallium (Tl), zinc (Zn), zirconium (Zr), and combinations thereof. Aluminum fluoride may be a preferred coating material because of its low cost and environmental benefits. Metal fluoride coatings are generally disclosed in published PCT application WO 2006 / 109930A to Sun et al. Entitled “Cathode Active Material Coated with Fluorine Compounds for Lithium Secondary Batteries”, incorporated herein by reference. This patent application provides results for LiCoO ₂ coated with LiF, ZnF ₂ or AlF ₃ . PCT Application line mentioned above, and specifically referred to the following fluoride compositions, such as: CsF, KF, LiF, NaF , RbF, TiF, AgF, AgF 2, BaF 2, CaF 2, CuF 2, CdF 2, FeF 2 , HgF ₂ , Hg ₂ F ₂ , MnF ₂ , MgF ₂ , NiF ₂ , PbF ₂ , SnF ₂ , SrF ₂ , XeF ₂ , ZnF ₂ , AlF ₃ , BF ₃ , BiF ₃ , CeF ₃ , CrF ₃ , DyF _{3 , EuF 3, GaF 3, GdF} 3, FeF 3, HoF 3, InF 3, LaF 3, LuF 3, MnF 3, NdF 3, VOF 3, PrF 3, SbF 3, ScF 3, SmF 3, TbF 3, TiF _{3, TmF 3, YF 3,} YbF 3, TlF 3, CeF 4, GeF 4, HfF 4, SiF 4, SnF 4, TiF 4, VF 4, ZrF 4, NbF 5, SbF 5, TaF 5, BiF 5, MoF ₅ , ReF ₅ , SF ₅ , and WF ₅ .

_{LiNi 1/3 CO 1/3} Mn 1/3 , such as the effect of the AlF ₃ coating on the cycle performance of the O ₂ line (Sun) "lithium secondary battery, _{Li [Ni 1/3 CO 1} /3 Mn 1/3] AlF ₃ -Coating to Enhance High Voltage Cycle Performance of O ₂ Cathode Materials ”is further described in J. of the Electrochemical Society, 154 (3), Al 68-Al 72 (2007). _{Also, LiNi 0 .8 CO 0 .1 Mn} 0 .1 , the effect of AlF ₃ coating on the cycle performance of the O _2, in the "AlF ₃ coating, such as a right (Woo), incorporated by reference herein, Li [Ni _0.8 CO A significant improvement in the electrochemical performance of _0.1 Mn _0.1 ] O ₂ cathode materials "is further described in J. of the Electrochemical Society, 154 (11) A1005- Al 009 (2007). Increasing capacity and decreasing irreversible capacity loss are described as "high capacity, surface-modified layered Li [Li _{(1-x) / 3} Mn with low irreversible capacity loss, such as Wu", incorporated herein by reference. Noted by Al ₂ O ₃ coating by the article _{(2-x) / 3} Ni _{x / 3} CO _{x / 3} ] O ₂ anode "(Electrochemical and Solid State Letters, 9 (5) A221-A224 (2006)) It became. The use of LiNiPO ₄ coatings to obtain improved cycle performance is described by Kang et al., "High Capacity xLi ₂ MnO ₃ (1-x) LiMO ₂ (M by Li-Ni-PO ₄ Treatment), incorporated herein by reference. = Improvement of charge / discharge efficiency of Mn, Ni, Co) electrodes "is disclosed in Electrochemistry Communications 11, 748-751 (2009).

Metal / metalloid fluoride coatings have been found to significantly improve the performance of lithium-rich layered compositions for lithium ion secondary batteries. For example, see U.S. Patent Application No. 12 / 616,226 to Lopez et al. Entitled &quot; Coated Anode Material for Lithium Ion Batteries, &quot; See also. It has been found that metal fluoride coatings further improve the performance of the doped material, especially when the amount of material is properly balanced. In particular, the coating improves the capacity of the battery. However, the coating itself is not electrochemically active. When the loss of specific capacity due to the thickness of the coating added to the sample exceeds the benefit of the coating addition being offset by its electrochemical inactivation, a reduction in battery capacity can be expected. In general, the amount of coating can be chosen to balance the favorable stabilization due to the coating with a loss of specific capacity due to the weight of the coating material, which generally does not directly contribute to the high specific content of the material.

However, the coating also affects other properties of the active material such as average voltage, thermal stability and impedance. The choice of coating properties can introduce additional factors related to the overall range of material properties. In general, the coating is within 25 nm, in some embodiments from about 0.5 nm to about 20 nm, in other embodiments from about 1 nm to about 12 nm, in still other embodiments from 1.25 nm to about 10 nm, and in further embodiments. It may have an average thickness of about 1.5 nm to about 8 nm in form. One of ordinary skill in the art will recognize that additional ranges of coating materials may be considered and are included in the present disclosure within the explicit scope set forth above. Effective amount of AlF ₃ in the metal oxide coating to the AlF ₃ to improve the capacity of the uncoated material is related to the particle size and surface area of the uncoated material. Further discussion of the effect of performance characteristics on coated lithium-rich metal oxides is described in US Pat. Appl. No. 12 of Lopez et al. Entitled “Coated Anode Materials for Lithium Ion Batteries”, incorporated herein by reference. / 616,226.

Fluoride coatings can be deposited using solution based precipitation methods. Powders of the positive electrode material can be mixed in a suitable solvent such as an aqueous solvent. Preferred water-soluble compositions of metal / metalloid can be dissolved in the solvent. NH ₄ F may then be added slowly to the dispersion to precipitate the metal fluoride. The total amount of coating reactant may be selected to form the desired amount of coating, and the proportion of coating reactant may be based on the stoichiometry of the coating material. The coating mixture may be heated for about 20 minutes to about 48 hours at an appropriate temperature in the range of about 60 ° C. to about 100 ° C. for the aqueous solution during the coating process to facilitate the coating process. After removing the coated electroactive material from the solution, the material may be dried and heated to a temperature of about 250 ° C. to about 600 ° C. for about 20 minutes to about 48 hours to complete the formation of the coated material. Heating may be performed under a nitrogen atmosphere or other substantially oxygen free atmosphere. The formation of inert metal oxide coatings such as Al ₂ O ₃ and Li-Ni-PO ₄ coatings is disclosed in the above cited references.

Battery performance

Batteries made with the doped cathode active materials disclosed herein show excellent performance under actual discharge conditions for applications of medium current. Specifically, the doped active material shows high average discharge voltage and high specific capacity during cycle of battery at medium discharge rate. In addition, the doped material may exhibit slightly reduced irreversible capacity loss, which will further enhance the reduction of the irreversible capacity loss of the first cycle of the coated electroactive material as compared to the corresponding undoped and uncoated material. Can be.

In general, several similar test procedures can be used to evaluate battery performance. Specific test procedures are disclosed for the evaluation of the performance values disclosed herein. Test procedures are described in more detail in the Examples below. Specifically, the battery may be cycled from 4.6 volts to 2.0 volts at room temperature, unless another temperature is specifically provided, but other voltage ranges may be used with corresponding different results. Evaluation in the range of 4.6 volts to 2.0 volts is preferred for commercial use because batteries with active materials disclosed herein generally have stable cycles in this voltage range. In some embodiments, during the first three cycles the battery is discharged at a rate of C / 10 to set the irreversible capacity loss. The battery then cycles at C / 5 for three cycles. For cycle 7 and above, the battery is cycled at a rate of C / 3, which is a suitable test rate for medium current applications. Again, the notation C / x means that the battery is discharged at the rate of discharging the battery to the selected voltage limit for x hours. The capacity of the battery has a reduced capacity with increasing discharge rate and is highly dependent on the discharge rate.

In some embodiments, the positive electrode active material has at least about 240 mAh / g (milli-amperes per gram) during the tenth cycle at a discharge rate of C / 3 and in further embodiments from about 250 mAh / g to about 270 mAh / g Has a specific capacity. Furthermore, the discharge capacity of the 40th cycle of the material is at least about 90% of the discharge capacity of the 10th cycle, at least about 94% in another embodiment and at least in other embodiments when cycled at a discharge rate of C / 3. May be about 95%. The irreversible capacity loss of the first cycle for the coated electroactive material can be within about 70 mAh / g, in another embodiment within about 60 mAh / g, and in further embodiments within about 55 mAh / g. . The tap density of the material measured as follows may be at least about 1.8 g / mL, in another embodiment about 2 to about 3.5 g / mL, and in further embodiments, about 2.05 to about 2.75 g / mL. Higher tap density translates into a higher overall capacity of a given battery in a fixed volume. Those skilled in the art will appreciate that additional ranges of specific amounts, reductions in specific capacity, cycle capacity, irreversible capacity loss and tap density, and irreversible capacity loss may be considered and are included in the present disclosure. In fixed volume applications such as batteries for electronic devices, high tap density, and therefore high overall capacity of the battery, is particularly important.

In general, the tap density is the apparent powder density that can be obtained under the specified conditions of tapping. The apparent density of the powder depends on how closely the individual particles of the powder are filled. Apparent density is affected by particle size distribution, particle shape and cohesion as well as true density of solids. Handling or vibration of the powder material can overcome some of the cohesion and cause the particles to move relative to each other, so that small particles can gradually enter the space between the large particles. As a result, the total volume occupied by the powder decreases and its density increases. Ultimately, no more packing of natural particles could be measured without the addition of pressure and maximum particle packing was achieved. The electrode is formed with the addition of pressure, but only an appropriate amount of pressure is effective to form a particular packing density of electroactive material at the battery electrode. The actual density in the electrode is generally related to the tap density measured for the powder, so the tap density measurement can predict the packing density in the battery electrode with the higher tap density corresponding to the higher packing density in the battery electrode. .

Under the controlled conditions of tap rate, drop height and vessel size, the tap density obtained can be highly reproduced. The tap density of the positive electrode active material disclosed herein can be measured by using a graduated measuring cylinder on a commercial tap machine having certain tapping parameters.

The average voltage of the material can be an important parameter. Higher average voltages may indicate the ability to deliver additional power. Moderate amounts of doping with +2 cations can lead to an increase in the average voltage, but other advantageous properties can also be used. In some embodiments, when discharged at a rate of C / 3 between 4.6 volts and 2.0 volts, the average voltage is at least about 3.60 volts, in another embodiment at least about 3.61 volts, and in further embodiments at least about 3.62 volts Can be. Those skilled in the art will appreciate that additional ranges of average voltages may be considered and are included in the present disclosure within the above stated ranges.

Example

Example  1: metal sulphate for carbonate coprecipitation and Na ₂ CO ₃ Of NH ₄ OH Reaction of

This example shows the preparation of the desired cathode active material using carbonate or hydroxide coprecipitation. A stoichiometric amount of metal precursor is dissolved in distilled water to form an aqueous solution with the metal in the desired molar ratio. Separately, an aqueous solution containing Na ₂ CO ₃ and / or NH ₄ OH was prepared. For the preparation of the sample, one or two solutions were slowly added to the reaction vessel to form a metal carbonate or hydroxide precipitate. The reaction mixture was stirred and the temperature of the reaction mixture was maintained between room temperature and 80 ° C. The pH of the reaction mixture ranged from approximately 6-12. In general, the transition metal aqueous solution had a concentration of 1 M to 3 M, and the Na ₂ CO ₃ / NH ₄ OH aqueous solution had a Na ₂ CO ₃ concentration of 1 M to 4 M and a NH ₄ OH concentration of 0.2 to 2 M. The metal carbonate or hydroxide precipitate was filtered, washed several times with distilled water and dried at 110 ° C. for 16 hours to prepare a metal carbonate or hydroxide powder. The specific range of reaction conditions for preparing the sample is further shown in Table 1, where the solution may not include both Na ₂ CO ₃ and NH ₄ OH.

Reaction Process Condition value Reaction pH 6.0-12.0 Reaction time 0.1-24 hours Reactor type Batch Reactor stirring speed 200-1,400 rpm Reaction temperature Room temperature-80 ℃ Metal salt concentration 1-3 M Na ₂ CO ₃ concentration 1-4 M NH ₄ OH concentration 0.2-2 M Flow rate of metal salt 1-100 mL / min Flow Rate of Na ₂ CO ₃ and NH ₄ OH 1-100 mL / min

An appropriate amount of Li ₂ CO ₃ powder was combined with the dried metal carbonate or hydroxide powder and thoroughly mixed with a Jar Mill, double planetary mixer or dry powder rotary mixer to produce a homogeneous powder mixture. A portion of the homogenized powder, for example 5 grams, was calcined in the step for oxide formation followed by an additional mixing step to further homogenize the powder. The more homogenized powder was calcined once more to produce a high crystalline lithium composite oxide. The resulting composition was determined to be generally represented by the formula Li1.2Ni0.175Mn0.525-yCO0.10MgyO2. Compositions ranging from 0 (not dope) to a y value of approximately 0.10 are disclosed in the following examples. The specific range of firing conditions is further shown in Table 2.

Firing process conditions naze First step Temperature 400-800 ℃ time 1-24 hours Protective gas Nitrogen or air Flow rate of protective gas 0-50 scfh 2nd step Temperature 700-1,100 ℃ time 1-36 hours Protective gas Nitrogen or air Flow rate of protective gas 0-50 scfh

The anode composite material particles thus formed generally have a spherical shape and are relatively homogeneous in size. As shown in FIG. 2, the X-ray diffraction pattern of 0.5%, 1%, 2%, 3%, and 5% magnesium doped cathode active material is generally the same as the undoped material. The undoped material and similar X-ray patterns of the doped material suggest that the general crystal structure characteristics of the material are not significantly altered by doping. The synthesized composite was then used to make a coin-type battery following the above procedure. Coin-type cell batteries were tested and the results are shown in the examples below.

The composition of the resulting material was confirmed by inductively coupled plasma-optical emission spectroscopy (ICP-OES). Samples were provided with ICP-OES for elemental analysis to confirm the presence of magnesium. This data confirms that the resulting composition contains magnesium.

Example  2: AlF ₃  Preparation of Coated Metal Oxides

This example describes the formation of an aluminum fluoride coating on lithium metal oxide particles. Battery performance characteristics of the coated particles are disclosed in later examples.

A portion of the lithium metal oxide particles prepared in Example 1 were coated with a layer of aluminum fluoride (AlF ₃ ) using a solution based method. For a selected amount of aluminum fluoride coating, an appropriate amount of saturated solution of aluminum nitrate was prepared in an aqueous solvent. The metal oxide particles were then added to the aluminum nitrate solution to form a mixture. After homogenization, a stoichiometric amount of ammonium fluoride was added to the homogenized mixture to form an aluminum fluoride precipitate that coats the lithium metal oxide particles. After addition of ammonium fluoride, the mixture was stirred at a temperature of 40 ° C. to 80 ° C. for 1 to 12 hours. The mixture was then filtered and the solid was washed repeatedly to remove all unreacted material. After washing, the solid was calcined for 2 to 24 hours in a nitrogen atmosphere of 400 to 600 ° C. to form an AlF ₃ coated metal oxide.

Specifically, samples of lithium metal oxide (LMO) particles synthesized as described in Example 1 were coated with aluminum fluoride to a thickness of 3 nm, 6 nm, 11 nm and 22 nm using the process described in this example. Lithium metal oxide coated with aluminum fluoride was used to produce a coin-type cell battery according to the above procedure, and the results are shown below.

Example  3: tap density results of different metal oxides

This example provides tap density values for doped metal oxides with or without an inert coating to show that good values of tap density for the positive electrode material disclosed herein can be achieved.

Tap densities of the samples synthesized in Examples 1 and 2 were measured using an AUTOTAP ™ machine from Quantachrome Instruments (Boynton Beach, Florida). In a general measurement procedure, the sample powder was weighed in 4 grams and placed in a graduated cylinder (10 mL). The cylinder was then mounted to the wheel of the autotap, tapping at a tap speed of 260 min ⁻¹ and a drop height of 3 mm. After 2,000 taps, the volume of the powder was determined using a measurement mark on a graduated cylinder. The initial weight of the sample divided by the volume measured after tapping represents the tap density in g / mL of the sample. Tap densities of the samples prepared as described in Examples 1 and 2 were measured and representative tap densities of 1.6 to 1.8 were obtained. A battery was made in the following examples using a material having this representative tap density.

battery Example  4-8

All of the coin-type cell batteries tested in Examples 4-8 were performed using a coin-type cell battery prepared according to the procedure described herein. To prepare the positive electrode composition, a lithium metal oxide (LMO) powder was thoroughly mixed with acetylene black (Super P ^{™ from} Timcal, Switzerland and KS 6 ^™ from Timcal, Switzerland) to prepare a homogeneous powder mixture. , polyvinylidene fluoride (PVDF polyvinylidene fluoride, Kureha Japan's KFl ^TM 300) to N- methyl-pyrrolidone (N-methyl-pyrrolidone NMP, Honeywell - Riedel-de-Haen) and were mixed and stirred overnight PVDF- A NMP solution was prepared A homogeneous powder mixture was added to the PVDF-NMP solution and mixed for 2 hours to produce a homogeneous slurry, using a doctor's blade coating process to apply the slurry to an aluminum foil current collector. It was applied to prepare a thin wet film (thin wet film).

An aluminum foil current collector having a thin humidity film was dried at 110 ° C. for approximately 2 hours to remove NMP to prepare a cathode material. The dried positive electrode material on the current collector was rolled between rollers of a sheet mill to obtain a positive electrode having a desired thickness. An example of a positive electrode composition having an 80: 5: 5: 10 weight ratio LMO: acetylene black: graphite: PVDF developed using the above process is shown below.

The anode was placed in an argon-filled glove box for the manufacture of coin cell batteries. Lithium metal foil was used as the negative electrode. The electrolyte was a 1 M LiPF ₆ solution prepared by dissolving a LiPF ₆ salt in a 1: 1: 1: 1 ethylene carbonate, diethyl carbonate and dimethyl carbonate mixture (Ferro, Ohio). A three layer (polypropylene-polyethylene-polypropylene) micro-porous separator (2320, Celgard, NC, USA) moistened with electrolyte was placed between the positive and negative electrodes. In addition, a few drops of electrolyte were added between the two electrodes. The electrodes were sealed inside a 2032 coin cell hardware (Hohsen, Japan) using a crimping process. The coin-shaped cell batteries formed were tested with a Maccor cycle tester to obtain charge-discharge curves and cycle stability for multiple cycles.

Example  5: Mg Doped  Capacity and Cycle of Lithium-Rich Oxide

This example shows the improved capacity and cycle performance of a coin-type cell made of magnesium doped lithium metal oxide with or without coating.

Coin-type cells were prepared from powders synthesized as described in Examples 1 and 2. The coin cell battery was discharged at C / 10 for 1 to 3 cycles, at a discharge rate of C / 5 for 4 to 6 cycles, at a discharge rate of C / 3 for 7 to 40 cycles, and for 41 to The test was conducted for 50 charge and discharge cycles at a discharge rate of 1 C for 45 cycles and a discharge rate of 2 C for 46 to 50 cycles. A graph of the specific discharge capacity versus cycle life of a coin type battery is shown in FIGS. 3-8. Specifically, the graphs shown in FIGS. 3, 4, 5, 6, 7, and 8 are each undoped, 0.5 mol%, 1.0 mol%, 2.0 mol%, 3.0 mol%, and are for the composite material comprising the magnesium of 5.0 mol%, wherein the molar percentage value corresponds to 100y for y as specified in the formula _{Li 1 .2 Ni 0 .175 Mn 0} .525-y CO 0.10 Mg y O 2. We note that at high rates, materials with 1 to 3 mol% magnesium have the highest specific capacity with the best coating thickness. Each figure contains a series of results for the uncoated material and various amounts of AlF ₃ coating material. The doses of undoped and uncoated materials were also shown in each figure and labeled "pristine" for comparison with the results for the doped samples. FIG. 9 comparing the specific discharge capacities for different values of Mg doping (pure-undoped, 0.5 mol%, 1.0 mol%, 2.0 mol%, 3.0 mol% and 5.0 mol%) for samples without an aluminum fluoride coating. Shown in the graph. Samples without Mg doping and AlF ₃ coating were included as controls. 9 can be compared between 2 mol% Mg and 3 mol% Mg, where the specific discharge capacity values are not purely-doped for 39 cycles, and the performance of the battery with Mg doped samples is higher at 1C. , 2C). From these graphs, samples with 2% and 3% Mg doping show the best performance in terms of specific capacity. Materials with 2 mol% Mg doping show the best cycle performance over the range of dopants and coatings tested.

The specific discharge capacity of the first cycle of a battery made of differently doped cathode materials with AlF ₃ coatings of varying thickness is shown in mole percentage of Mg, and the results are shown in FIG. 10. As shown in FIG. 10, a battery made from a positive electrode material without an AlF ₃ coating exhibited the lowest total specific capacity of the first cycle, regardless of the mole percentage of Mg doping. Batteries made from positive electrode materials with AlF ₃ coatings of 3 nm, 6 nm, and 11 nm exhibited similar total specific capacity of the first cycle over the mole percentage of Mg doping, which resulted in an AlF ₃ coating of 22 nm. It is better than those of the anode material having.

Likewise, the specific discharge capacity of the ninth cycle of a battery made from differently doped anode materials with various thicknesses of AlF ₃ coatings is expressed as mole percentage of Mg, and the results are shown in FIG. 11. As shown in FIG. 11 and as in FIG. 10, a battery made from a positive electrode material without an AlF ₃ coating exhibited the lowest total specific capacity of the ninth cycle, regardless of the mole percentage of Mg doping. Batteries made from positive electrode materials with AlF ₃ coatings of 3 nm, 6 nm, and 11 nm exhibited similar specific specific amounts of the ninth cycle over the mole percentage of Mg doping, which resulted in a 22 nm AlF ₃ coating. It is better than those of the anode material having.

The specific discharge capacity of the 41st cycle for the positive electrode active material having various AlF ₃ coating thicknesses is shown in FIG. 12 as the molar percentage of Mg. In the 41st cycle, the cell was charged at a rate of C / 5 and discharged at a rate of 1C. Again, batteries made with uncoated samples and samples with a 22 nm thick coating tended to have the lowest capacity. In AlF ₃ surface coated samples of 3 nm and 6 nm, higher specific discharge capacities were observed at these higher rates for batteries with Mg doping (2, 3 mol%). The result of the specific discharge capacity does not follow this tendency when the coating thickness increases to values of 11 nm and 22 nm.

In addition, the specific discharge capacity of the 46th cycle for the positive electrode active material having various AlF ₃ coating thicknesses is shown in FIG. 13 as the molar percentage of Mg. In the 46th cycle, the discharge rate was 2C. This result shows a large change with the amount of Mg doping. However, batteries made from samples with AlF ₃ coatings of 3 nm or 6 nm generally had the largest specific discharge capacity. At these higher discharge rates, moderate amounts of Mg coating resulted in an increase in specific discharge capacity compared to batteries with undoped samples for both uncoated and coated samples.

Example  6: Mg Doped  Average Voltage for Batteries with Compositions

This example shows that results of relatively high average voltages can be achieved with Mg doped compositions.

The average voltage was obtained in the first discharge cycle during the discharge from 4.6 V to 2 V with a discharge rate of C / 10. A graph of the average voltage as a function of the amount of AlF ₃ coating of various Mg doped materials is shown in FIG. 14A. 14A shows that the average voltage of the first discharge cycle of the battery decreases with increasing thickness of the AlF ₃ coating. A graph of the average voltage as a function of various Mg doped materials without coating is shown in FIG. 14B. Both 14A and 14B show that 0.5 mol% and 1.0 mol% Mg doped material has a higher average voltage of the first discharge cycle than other compositions. A graph of the average voltage as a function of the mole percentage of Mg doped material with various AlF ₃ coating thicknesses is shown in FIG. 15, where the sample with AlF ₃ coating of 22 nm shows the minimum average voltage.

The average voltage of the first discharge cycle of the battery decreases with increasing thickness of the AlF ₃ coating.

Example  7: Mg Doped  Irreversible capacity loss for the sample

This example shows the reduction of irreversible capacity loss for the sample, where the anode comprises Mg doped material.

As mentioned above, the irreversible capacity loss is the difference between the first charge capacity and the first discharge capacity for the battery. As described in Example 2, a coin-type cell battery was prepared using the doped cathode active material described in Example 1 with an optional AlF ₃ coating. A graph of irreversible capacity loss as a function of coating thickness is shown in FIG. 16A. For samples without coatings, a graph of irreversible capacity loss as a function of Mg doping level is shown in FIG. 16B.

A graph of irreversible capacity loss as a function of the mole percentage of Mg with various AlF ₃ coating amounts is shown in FIG. 17. In general, both the addition of Mg dopant and coating reduces irreversible capacity loss.

Example  8: Impedance measurement

This example performs complex impedance measurements on a battery made of metal oxide synthesized as described in Example 1 with evidence that the magnesium dopant can improve the charge and discharge efficiency of the prepared material.

Coin-type cells were made from lithium-rich metal oxides without fluoride coating. AC power was applied to the electrodes at various frequencies. Complex impedance is evaluated from current measurements with AC voltage. Analysis of complex impedance measurements is described in Ho et al., "Application of AC Technology to the Study of Lithium Diffusion in Tungsten Trioxide Thin Films", incorporated herein by reference (Semiconductor Electrodes 127 (2), February 1980 343-350). In the first series of experiments, the battery was charged to 4.6 V in the initial charging stage before performing the impedance measurement.

Complex impedance measurements are shown in FIGS. 18 and 19. 19 is an enlarged view of a portion of the graph of FIG. 18. The radius of the initial curve portion is related to the charge transfer resistance. Samples with 3 mol% and 5 mol% magnesium show reduced amounts of charge transfer resistance. Referring to FIG. 18, the upward slope slope section is related to the diffusion rate of lithium from the electrode. The diffusion constant is estimated from the formula:

DLi = (2πΖ _imag FreqL ² ) / (Ζ _real ),

Where L is the thickness of the electrode. The values of mag _imag and Ζ _real are evaluated at low frequency points of 4.53 × 10 ^-3 Hz. Diffusion coefficients for a battery made from a composition having three different Mg doping levels and an undoped composition are shown in FIG. 20. The diffusion constant is larger for the doped sample, indicating that lithium can diffuse more easily from the electrode with magnesium doping.

The complex impedance measurement was repeated after the battery was discharged to 50% or less of charge. In other words, the current capacity of the battery was almost discharged before the A-C current measurement was performed. The result is shown in FIG. Two charge transfer steps can be seen in this graph. Batteries made with positive electrode material with 5 mol% magnesium have increased charge transfer resistance in this charging step, while batteries with 1 mol% and 3 mol% Mg are lower than batteries made with undoped material. Had charge transfer resistance. This result is consistent with a battery prepared with 3 mol% Mg doping, showing the best performance at a high discharge rate of 2C as shown in FIG. 9. In other words, the complex impedance measurement is consistent with the improved specific capacity at high speeds previously observed with respect to battery performance.

The above-described embodiments are for illustrative purposes and do not limit. Further embodiments are within the scope of the claims. In addition, while the invention has been described with reference to specific embodiments, those skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. All documents incorporated by reference above are limited such that no subject matter is contrary to the clear disclosure herein.

Claims (29)

In the positive electrode active material comprising a composition having the formula Li _{1 + x} Ni _α Mn _β-δ Co _γ A _δ X _μ O _{2 - z} F _z ,
Where x is in the range of about 0.01 to about 0.3,
α ranges from about 0.1 to about 0.4,
β ranges from approximately 0.25 to approximately 0.65,
γ is in the range of about 0 to about 0.4,
δ ranges from approximately 0.001 to approximately 0.15,
μ ranges from 0 to approximately 0.1,
z ranges from 0 to approximately 0.2,
Where A is magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), cadmium (Cd), or a combination thereof, and X is A, nickel (Ni), manganese (Mn) ) And a transition metal different from cobalt (Co). The method of claim 1,
The positive electrode active material, wherein the sum of x + α + β + γ + δ + μ is approximately 1.0. The method of claim 1,
δ is approximately 0.0025 to approximately 0.04. The method of claim 1,
A is magnesium,
X ranges from 0.175 to approximately 0.225,
α ranges from about 0.150 to about 0.2,
β ranges from approximately 0.52 to approximately 0.57,
γ ranges from approximately 0.075 to approximately 0.125,
δ is in the range of approximately 0.01 to approximately 0.05. The method of claim 1,
z is 0 and the material comprises a metal fluoride coating in an amount of about 3 nm to about 11 nm. The method of claim 5, wherein
The metal fluoride includes AlF ₃ positive electrode active material, characterized in that. The method of claim 1,
Wherein the material has a discharge capacity of at least approximately ten mAh cycles at room temperature at a discharge rate of C / 3 when discharged from 4.6 volts to 2.0 volts at room temperature. The method of claim 1,
Wherein the material has a discharge capacity of at least about 250 mAh / g to about 270 mAh / g at tenth cycle at room temperature with a discharge rate of C / 3 when discharged from 4.6 volts to 2.0 volts. The method of claim 1,
A cathode active material, having a tap density of at least approximately 1.8 g / mL. The method of claim 1,
A positive electrode active material, having an irreversible capacity loss of the first cycle within approximately 70 mAh / g at a discharge rate of C / 10. The positive electrode active material of Claim 1 containing an electrically conductive material different from the said positive electrode active material, and a binder. An average discharge voltage of at least approximately 3.63 volts at a discharge rate of C / 10, a discharge capacity of at least approximately 240 mAh / g at room temperature at a discharge rate of C / 3 when discharged from 4.6 volts to 2.0 volts at room temperature, and
Discharge capacity of at least approximately 90% of the discharge capacity of the tenth cycle when cycled between the tenth and forty cycles at room temperature with a discharge rate of C / 3 from 4.6 volts to 2.0 volts A cathode active material for a lithium ion battery, characterized by having a. 13. The method of claim 12,
Formula _{Li 1 + x Ni α Mn β} -δ Co γ A δ X μ O 2 - comprises a composition represented by the _z F _z, and
Where x is in the range of about 0.01 to about 0.3,
α ranges from about 0.1 to about 0.4,
β ranges from approximately 0.25 to approximately 0.65,
γ is in the range of about 0 to about 0.4,
δ ranges from approximately 0.001 to approximately 0.15,
μ ranges from 0 to approximately 0.1,
z ranges from 0 to approximately 0.2,
Where A is magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), cadmium (Cd), or a combination thereof, and X is A, nickel (Ni), manganese (Mn) ) And a transition metal different from cobalt (Co). The method of claim 13,
The positive electrode active material, wherein the sum of x + α + β + γ + δ + μ is approximately 1.0. The method of claim 13,
A is magnesium (Mg) and δ is about 0.005 to about 0.04, the positive electrode active material. 13. The method of claim 12,
z is 0 and the material comprises a metal fluoride coating of approximately 3 nm to approximately 11 nm. 13. The method of claim 12,
Wherein the material has a discharge capacity of at least about 250 mAh / g to about 270 mAh / g at tenth cycle at room temperature with a discharge rate of C / 3 when discharged from 4.6 volts to 2.0 volts. 13. The method of claim 12,
A cathode active material, having a tap density of at least approximately 1.8 g / mL. A lithium ion secondary battery comprising a positive electrode including the positive electrode active material of claim 12, a negative electrode containing elemental carbon, and a separator plate between the positive electrode and the negative electrode. The method of claim 19,
The battery has a capacity of at least approximately 95% in the 40th cycle compared to the 10th cycle at a discharge rate of C / 3 from 4.6 to 2.0 V during the 10th to 40th cycles battery. A method for the synthesis of layered lithium metal oxides, the method comprising the step of precipitating a mixed metal hydroxide or carbonate component from a solution comprising a +2 metal cation, wherein the mixed metal hydroxide or carbonate component is from about 0.1 to about Selected stoichiometry including Ni ⁺² , Mn ⁺² , Co ⁺² with a dopant concentration of 10 mol%, wherein the dopant is magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) , Zinc (Zn), cadmium (Cd) or a combination thereof. 22. The method of claim 21,
Adding a lithium source in powder form to the metal hydroxide or carbonate component to form a mixture and heating the mixture to form corresponding crystalline lithium metal oxide particles. 22. The method of claim 21,
The lithium metal oxide particles include a composition represented by the formula Li _{1 + x} Ni _α Mn _β-δ Co _γ A _δ X _μ O _{2 - z} F _z ,
Where x is in the range of about 0.01 to about 0.3,
δ ranges from approximately 0.001 to approximately 0.15,
α ranges from about 0.1 to about 0.4,
β ranges from approximately 0.25 to approximately 0.65,
γ is in the range of about 0 to about 0.4,
μ ranges from 0 to approximately 0.1,
z ranges from 0 to approximately 0.2,
Where A is magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), cadmium (Cd), or a combination thereof, and X is A, nickel (Ni), manganese (Mn) ) And a transition metal different from cobalt (Co). 24. The method of claim 23,
Mixing the lithium metal oxide particles with an aluminum salt solution and then mixing with a salt containing fluoride ions to form an aluminum fluoride precipitate, which is then heated to form aluminum fluoride coated lithium metal oxide particles. How to feature. 25. The method of claim 24,
Lithium metal oxide particles coated with aluminum fluoride have a specific discharge capacity of at least 240 mAh / g at room temperature with a discharge rate of C / 3 when discharged from 4.6 volts to 2.0 volts in a lithium ion battery. An average discharge voltage of at least approximately 3.63 volts at a discharge rate of C / 10, a discharge capacity of at least approximately 240 mAh / g at room temperature at a discharge rate of C / 3 when discharged from 4.6 volts to 2.0 volts at room temperature, and
A positive electrode active material for a lithium ion battery, having a discharge capacity of at least about 46 mAh / g at least about 46 mAh / g at room temperature with a discharge rate of 4.6 volts to 2.0 volts. The method of claim 26,
Formula _{Li 1 + x Ni α Mn β} -δ Co γ A δ X μ O 2 - comprises a composition represented by the _z F _z, and
Where x is in the range of about 0.01 to about 0.3,
α ranges from about 0.1 to about 0.4,
β ranges from approximately 0.25 to approximately 0.65,
γ is in the range of about 0 to about 0.4,
δ ranges from approximately 0.001 to approximately 0.15,
μ ranges from 0 to approximately 0.1,
z ranges from 0 to approximately 0.2,
Where A is magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn), cadmium (Cd), or a combination thereof, and X is A, nickel (Ni), manganese (Mn) ) And a transition metal different from cobalt (Co). The method of claim 26,
The positive electrode active material, wherein the sum of x + α + β + γ + δ + μ is approximately 1.0. The method of claim 26,
A is magnesium (Mg) and δ is about 0.005 to about 0.04, the positive electrode active material.

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